1. Field of the Invention
The present invention relates to an apparatus for manufacturing a liquid crystal display, and more particularly, to a substrate loading/unloading apparatus used in manufacturing a liquid crystal display.
2. Discussion of the Related Art
In response to an increased demand for various types of display devices, flat panel type displays such as liquid crystal display (LCD), plasma display panel (PDP), electro-luminescent display (ELD), and vacuum fluorescent display (VFD) have been developed. In particular, LCD devices are commonly used because of their high resolution, light weight, thin profile, and low power consumption. In addition, LCD devices are commonly implemented for mobile devices, such as monitors for notebook computers, and for monitors of computers and televisions.
LCD devices are provided with an LCD panel for displaying image data, and a driving unit for applying a driving signal to the LCD panel. The LCD panel is provided with first and second glass substrates bonded at a certain distance with liquid crystal material injected therebetween. A plurality of gate lines are formed along a first direction at fixed intervals on the first glass substrate (i.e., TFT array substrate), and a plurality of data lines are formed along a second direction perpendicular to the first direction, thereby defining a plurality of pixel regions. A plurality of pixel electrodes are formed in a matrix arrangement at the pixel regions, and a plurality of thin film transistors (TFT) are formed at the pixel regions. Accordingly, the plurality of thin film transistors are enabled by signals transmitted along the gate lines and transfer signals transmitted along the data lines to each pixel electrode.
In order to prevent light leakage, black matrix films are formed on the second glass substrate (i.e., color filter substrate) except at regions of the second glass substrate corresponding to the pixel regions of the first glass substrate. Also, a red, green, and blue color filter substrate is formed on the second glass substrate to produce colored light, and a common electrode is formed on the color filter substrate to produce images.
Processes for manufacturing an LCD device include injection and drop methods. The injection method according to the prior art includes steps of forming a sealant pattern on one of the first and second substrates to form an injection inlet, bonding the first and second substrates to each other within a vacuum processing chamber, and injecting liquid crystal material through the injection inlet. The drop method according to the prior art, which is disclosed in Japanese Patent Application Nos. 11-089612 and 11-172903, includes steps of dropping liquid crystal material on a first substrate, arranging a second substrate over the first substrate, and moving the first and second substrates to be adjacent to each other, thereby bonding the first and second substrates to each other.
FIG. 1A is a plane view of a manufacturing apparatus of a liquid crystal display device according to the related art. In FIG. 1A, the manufacturing apparatus uses the liquid crystal injecting method and includes a bonding unit 11 for bonding first and second glass substrates together, a hardening unit 12 for hardening the bonded substrates, an injecting unit 13 for injecting a liquid crystal material through an injecting hole into the space formed between the bonded substrates, a sealing unit 14 for sealing the injecting hole, a cleaning unit 15 for cleaning the liquid crystal material-injected panel, and a substrate loading/unloading unit 16 for selectively loading/unloading the bonded substrates from one unit to another.
The liquid crystal injecting method includes steps of depositing and drying a sealant on the first substrate by a sealant dispensing unit and a sealant drying unit that are arranged along a first processing line. Simultaneously, the second glass substrate passes through a second processing line having a silver dotting unit for depositing dots of silver on the second glass substrate, and a spacer dispersion unit for dispersing spacers on the second glass substrate.
Next, the first and second glass substrates are transferred to the bonding unit 11 by the substrate loading/unloading unit 16, and bonded together by the bonding unit 11. Then, the bonded substrates are transferred to the hardening unit 12 by the substrate loading/unloading unit 16. The bonded substrates are separated by a certain distance by the spacer, thereby forming a cavity spaced, and an injecting hole is formed at a certain region along a circumference of the bonded substrates.
Then, the bonded substrates are hardened at the hardening unit 12, and are transferred to the liquid crystal material injecting unit by the substrate loading/unloading unit 16. Subsequently, a liquid crystal material is injected by the injecting unit 13 through the injecting hole into the cavity space formed between the bonded substrates, and the injecting hole is sealed by the sealing unit 14. Then, the bonded substrates are cleaned by the cleaning unit 15, thereby completing the process of manufacturing the LCD device.
FIG. 1B is a plane view of a manufacturing apparatus of a liquid crystal display device according to the related art. In FIG. 1B, the manufacturing apparatus uses the liquid crystal dropping method and includes a bonding unit 21 for bonding a first glass substrate, which has sealant and liquid crystal material deposited thereon, and a second glass substrate together, a hardening unit 22 for hardening the bonded substrates, a cutting unit 23 for cutting the hardened bonded substrates in a unit of an LCD device, and a substrate loading/unloading unit 16 for selectively loading/unloading the bonded substrates from one unit to another.
The liquid crystal dropping method includes steps of depositing liquid crystal material and sealant on either of a first or second substrate, and loading both the first and second substrates into a bonding unit 21 using a substrate loading/unloading unit 16. After bonding the first and second substrates, the bonded substrates are unloaded from the bonding unit 21 by the substrate loading/unloading unit 16. The bonded substrates unloaded from the bonding unit 21 are now transferred to the hardening unit 22 to perform a hardening process thereon.
and The bonded substrates may undergo a hardening process, which may include a thermal-hardening process using application of heat, in the hardening unit 22 for a certain time, and are then unloaded from the hardening unit 22 by the substrate loading/unloading unit 16. Subsequently, the bonded substrates unloaded from the hardening unit 22 are transferred into the cutting unit 23, and undergo a cutting process to produce individual display units, thereby completing the manufacturing of the liquid crystal panel.
FIG. 2 is a plane view of a substrate loading/unloading unit for manufacturing a liquid crystal display device according to the related art. The manufacturing apparatus using the liquid crystal injecting method and the liquid crystal dropping method according to the prior art requires repeated loading/unloading an individual substrate or bonded substrates using the substrate loading/unloading unit 16. However, the related art substrate loading/unloading unit 16 does not reliably perform the loading/unloading operation.
First, contact regions between the substrates and the loading/unloading unit 16 have the same shape and configuration. Thus, one substrate loading/unloading unit cannot be easily reconfigured to accommodate substrates having different geometries or sizes.
Second, a temperature difference between the different contact regions of the substrates and a portion of the substrate loading/unloading unit causes a thermal gradient during transfer of the hardened and bonded substrates unloaded from the hardening unit because the temperatures of the bonded substrates heated during the hardening process and the substrate loading/unloading unit for loading/unloading the heated substrates in the hardening unit are different. Accordingly, the portions of the bonded substrates that contact the substrate loading/unloading unit are distorted due to the temperature difference.
For example, the temperature of the finger part of the substrate loading/unloading unit is about room temperature and the temperature of the hardening-completed substrates is about 100˜150° C. (nominally 120° C.). Accordingly, a significant amount of heat transfer occurs at each contact region where the hardening-completed substrates contact the finger part of the substrate loading/unloading unit. Thus, each of the contact regions significantly distort the hardening-completed substrates.